The principal contradiction within capitalism from the outset was that between the capitalists and the workers. To keep their system going, the capitalists had constantly to step up the rate of exploitation of their workers. At the same time, European workers were gaining increasing mastery over the means of production in the factories and mines, and they were learning to work collectively in big enterprises and within their own trade union structures. If the bourgeoisie continued to deprive them of the major part of the fruits of their own labor and to oppress them socially and politically, then those two classes were set on a collision path. Ever since the mid-nineteenth century, Marx had predicted class collision would come in the form of revolution in which workers would emerge victorious. The capitalists were terribly afraid of that possibility, knowing full well that they themselves had seized power from the feudal landlord class by means of revolution.